The move by Zinke has garnered sharp criticism from congressional Democrats.

“Secretary Zinke would rather take money directly out of the pockets of hardworking Americans instead of coming up with a serious budget proposal for the National Park System,” said Representative Raúl Grijalva of Arizona.

Others points out that the proposed fee hike could make the cost of visiting a national park prohibitive for many American families.

Theresa Pierno, president and CEO of the nonpartisan National Parks Conservation Association, said in a statement that, “We should not increase fees to such a degree as to make these places — protected for all Americans to experience — unaffordable for some families to visit.”